The utility of neutron generators in various endeavors is well known. Neutron generators are commonly used, for instance, in areas as diverse as oil well logging applications, and treatment/monitoring of medical conditions. Conventional high fluence, non-active, neutron generator technology is mostly based on vacuum accelerator or RF techniques. The most basic neutron generator uses high voltage to accelerate deuterium (D) ions. The accelerated ions impact on a metal target loaded with tritium (T) gas, causing a deuterium-tritium (DT) fusion reaction that produces neutrons. Such devices appeared in the literature in the early 1960's, and the design continues to evolve with variations on the accelerator type, power supply driver type, size, and output.
A conventional neutron generator includes 1) a deuterium ion source, 2) an accelerating cavity, also termed an acceleration gap, or drift region, 3) an extraction plate disposed between the ion source region and the accelerating cavity, including an aperture for extracting the ions, and 4) the aforementioned metal target loaded with tritium. Most commercial deuterium ion sources are of the Penning type, which produces ions by heating a filament of wire (e.g., titanium) that has been hydrided with deuterium. As the temperature of the wire increases, the deuterium is released from the metal as a gas that is then ionized by a spark produced between a pair of electrodes. The deuterium ions are channeled through the aperture into the acceleration gap. At the end of the acceleration gap is the metal (e.g., titanium) target, which has been hydrided with tritium. The deuterium ions are accelerated across the gap by a high voltage applied between the extraction plate and the target.
Conventional neutron generators typically use a cylindrically symmetric discharge geometry, and are thus commonly referred to as neutron tubes. The cylindrical geometry facilitates ion beam control and symmetrical radial beam expansion. This symmetric geometry, although simple and effective, is not easily scaled down, thereby disadvantageously limiting the possibilities of size reductions.
It is desirable in view of the foregoing to provide a neutron generator that avoids disadvantages associated with prior art neutron generators.